1. Field of Invention
The present invention relates to an electronic device that sets the time based on signals received from a GPS satellite, for example, and to a time correction method for the electronic device.
2. Description of the Related Art
The Global Positioning System (GPS), which is a system enabling a receiving device to determine its own position, uses satellites (GPS satellites) that each orbit the Earth on a specific path. Each GPS satellite has an on-board atomic clock and keeps time with extremely high precision.
Japanese Unexamined Patent Appl. Pub. 08-15463 (see the abstract), for example, teaches a method of using data from the atomic clock of a GPS satellite to correct the time kept by a timepiece with high precision.
However, in order to get atomic clock data from a GPS satellite, the GPS receiver must first capture a signal from a GPS satellite orbiting the Earth and synchronize with the GPS satellite signal.
When the receiver that receives the signals from the GPS satellites is embedded in an electronic device such as a wristwatch, however, the receiver moves with user of the electronic device (wristwatch) wherever the user travels around the Earth.
Depending on the location of the user, tall buildings and other structures can interfere with signal reception from the orbiting GPS satellites, and it may therefore take a long time to adjust the time kept by the timepiece.
When the user is indoors in a building, it can be particularly difficult for the receiver to receive signals from the GPS satellites.
In order for the receiver to locate a GPS satellite and receive a signal under such conditions it may be necessary to drive the receiver for a long time. This obviously increases power consumption by the electronic device.
Timepieces and many other electronic devices, however, require very little power. Incorporating a high power consumption GPS receiver such as described while also satisfying the low power supply requirement of small electronic devices such as timepieces is therefore difficult, and adjusting the time kept by a timepiece in an electronic device with high precision is therefore not possible.